Surgical method for positioning a diagnostic or therapeutic element on the epicardium or other organ surface

ABSTRACT

Surgical methods for positioning diagnostic an therapeutic elements on the epicardium or other organ surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.09/072,872, filed May 5, 1998, now U.S. Pat. No. 6,142,994, which isitself a continuation-in-part of U.S. application Ser. No. 08/949,084,filed Oct. 10, 1997, now abandoned.

This application is also a continuation-in-part of U.S. application Ser.No. 09/017,465, filed Feb. 2, 1998, now U.S. Pat. No. 6,071,274.

The specification and claims of each of these applications areincorporated herein by reference.

BACKGROUND OF THE INVENTIONS

1. Field of Inventions

The present inventions relate generally to structures for positioningdiagnostic and therapeutic elements within the body and, moreparticularly, to devices which are particularly well suited for thetreatment of cardiac conditions.

2. Description of the Related Art

There are many instances where diagnostic and therapeutic elements mustbe inserted into the body. One instance involves the treatment ofcardiac conditions such as atrial fibrillation and atrial flutter whichlead to an unpleasant, irregular heart beat, called arrhythmia.

Normal sinus rhythm of the heart begins with the sinoatrial node (or “SAnode”) generating an electrical impulse. The impulse usually propagatesuniformly across the right and left atria and the atrial septum to theatrioventricular node (or “AV node”). This propagation causes the atriato contract in an organized way to transport blood from the atria to theventricles, and to provide timed stimulation of the ventricles. The AVnode regulates the propagation delay to the atrioventricular bundle (or“HIS” bundle). This coordination of the electrical activity of the heartcauses atrial systole during ventricular diastole. This, in turn,improves the mechanical function of the heart. Atrial fibrillationoccurs when anatomical obstacles in the heart disrupt the normallyuniform propagation of electrical impulses in the atria. Theseanatomical obstacles (called “conduction blocks”) can cause theelectrical impulse to degenerate into several circular wavelets thatcirculate about the obstacles. These wavelets, called “reentrycircuits,” disrupt the normally uniform activation of the left and rightatria.

Because of a loss of atrioventricular synchrony, the people who sufferfrom atrial fibrillation and flutter also suffer the consequences ofimpaired hemodynamics and loss of cardiac efficiency. They are also atgreater risk of stroke and other thromboembolic complications because ofloss of effective contraction and atrial stasis.

Although pharmacological treatment is available for atrial fibrillationand flutter, the treatment is far from perfect. For example, certainantiarrhythmic drugs, like quinidine and procainamide, can reduce boththe incidence and the duration of atrial fibrillation episodes. Yet,these drugs often fail to maintain sinus rhythm in the patient.Cardioactive drugs, like digitalis, Beta blockers, and calcium channelblockers, can also be given to control the ventricular response.However, many people are intolerant to such drugs. Anticoagulant therapyalso combats thromboembolic complications, but does not eliminate them.Unfortunately, pharmacological remedies often do not remedy thesubjective symptoms associated with an irregular heartbeat. They also donot restore cardiac hemodynamics to normal and remove the risk ofthromboembolism.

Many believe that the only way to really treat all three detrimentalresults of atrial fibrillation and flutter is to actively interrupt allof the potential pathways for atrial reentry circuits.

One surgical method of treating atrial fibrillation by interruptingpathways for reentry circuits is the so-called “maze procedure” whichrelies on a prescribed pattern of incisions to anatomically create aconvoluted path, or maze, for electrical propagation within the left andright atria. The incisions direct the electrical impulse from the SAnode along a specified route through all regions of both atria, causinguniform contraction required for normal atrial transport function. Theincisions finally direct the impulse to the AV node to activate theventricles, restoring normal atrioventricular synchrony. The incisionsare also carefully placed to interrupt the conduction routes of the mostcommon reentry circuits. The maze procedure has been found veryeffective in curing atrial fibrillation. However, the maze procedure istechnically difficult to do. It also requires open heart surgery and isvery expensive. Thus, despite its considerable clinical success, only afew maze procedures are done each year.

Maze-like procedures have also been developed utilizing catheters whichcan form lesions on the endocardium to effectively create a maze forelectrical conduction in a predetermined path. Exemplary catheters aredisclosed in commonly assigned U.S. Pat. No. 5,582,609. Typically, thelesions are formed by ablating tissue with an electrode carried by thecatheter. Electromagnetic radio frequency (“RF”) energy applied by theelectrode heats, and eventually kills (i.e. “ablates”), the tissue toform a lesion. During the ablation of soft tissue (i.e. tissue otherthan blood, bone and connective tissue), tissue coagulation occurs andit is the coagulation that kills the tissue. Thus, references to theablation of soft tissue are necessarily references to soft tissuecoagulation. “Tissue coagulation” is the process of cross-linkingproteins in tissue to cause the tissue to jell. In soft tissue, it isthe fluid within the tissue cell membranes that jells to kill the cells,thereby killing the tissue.

Catheters used to create lesions (the lesions being 3 to 15 cm inlength) typically include a relatively long and relatively flexible bodyportion that has an electrode on its distal end. The portion of thecatheter body portion that is inserted into the patient is typicallyfrom 23 to 55 inches in length and there may be another 8 to 15 inches,including a handle, outside the patient. The proximal end of thecatheter body is connected to the handle which includes steeringcontrols. The length and flexibility of the catheter body allow thecatheter to be inserted into a main vein or artery (typically thefemoral artery), directed into the interior of the heart, and thenmanipulated such that the electrode contacts the tissue that is to beablated. Fluoroscopic imaging is used to provide the physician with avisual indication of the location of the catheter.

Catheter-based soft tissue coagulation has proven to be a significantadvance in the medical arts generally and in the treatment of cardiacconditions in particular. Nevertheless, the inventors herein havedetermined that catheter-based procedures are not appropriate in everysituation and that conventional catheters are not capable of reliablyforming all types of lesions. One lesion that has proven to be difficultto form with conventional catheters is the circumferential lesion thatis used to isolate a pulmonary vein and cure ectopic atrialfibrillation. Lesions that isolate the pulmonary vein may be formedwithin the pulmonary vein itself or in the tissue surrounding thepulmonary vein. These circumferential lesions are formed by dragging atip electrode around the pulmonary vein or by creating a group ofinterconnected curvilinear lesions one-by-one around the pulmonary vein.Such techniques have proven to be less than effective because they areslow and gaps of conductive tissue can remain after the procedure. Itcan also be difficult to achieve adequate tissue contact withconventional catheters.

Endocardial lesions to isolate pulmonary veins have also been formed asa secondary procedure during a primary open heart surgical proceduresuch as mitral valve replacement. A surgical soft tissue coagulationprobe is used to form the endocardial lesions after the heart has beenopened, either before or after the valve replacement. This techniquedoes, however, increase the amount of time the patient is on pulmonarybypass, which can be undesirable.

Accordingly, the inventors herein have determined that a need exists forsurgical methods and apparatus that can be used to create lesions aroundbodily structures and, in the context of the treatment of atrialfibrillation, around a pulmonary vein without increasing the amount oftime that the patient is on pulmonary bypass.

SUMMARY OF THE INVENTIONS

Accordingly, the general object of the present inventions is to providemethods and apparatus that avoid, for practical purposes, theaforementioned problems. In particular, one object of the presentinventions is to provide surgical methods and apparatus that can be usedto create lesions around a pulmonary vein or other body structure in amore efficient manner than conventional apparatus. Another object of thepresent inventions is to provide surgical methods and apparatus that maybe used to create lesions around a pulmonary vein without placing thepatient on pulmonary bypass or increasing the amount of time that thepatient is on pulmonary bypass when a related procedure is beingperformed. Still another object of the present inventions is to performa diagnostic or therapeutic procedure, such as the coagulation of tissuearound a body structure, without effecting collateral tissue that is nottargeted for the procedure.

In order to accomplish some of these and other objectives, a surgicaldevice in accordance with a present invention includes a relativelyshort outer member, a relatively short shaft located at least partiallywithin the relatively short outer member and slidable relative to therelatively short outer member, and an operative element on the distalportion of the relatively short shaft. The distal portion of therelatively short shaft is adapted to be connected to the distal portionof the relatively short outer member such that the distal portion of theshaft member will form a loop.

In order to accomplish some of these and other objectives, a surgicaldevice in accordance with a present invention includes a relativelyshort outer member, a relatively short shaft located at least partiallywithin the relatively short outer member and slidable relative to therelatively short outer member, a control element defining a distalportion connected to the distal portion of the relatively short shaftand a proximal portion extending toward the proximal portion of therelatively short outer member, and an operative element on the distalportion of the relatively short shaft. The distal portion of therelatively short shaft may be used to form a loop.

In order to accomplish some of these and other objectives, a surgicaldevice in accordance with a preferred embodiment of a present inventionincludes a relatively short shaft and a distal member having a flexibleregion and a malleable region and an operative element carried by thedistal member. Preferably, the distal tip assembly may, if desired, alsoinclude a pull wire that facilitates the formation of a loop.

In order to accomplish some of these and other objectives, a clampdevice in accordance with a preferred embodiment of a present inventionincludes first and second curved members and a tissue coagulationapparatus associated with the first and second curved members. Thecurved members and tissue coagulation apparatus preferably togetherdefine an open region that may be positioned around a body structuresuch as one or more pulmonary veins.

Such devices provide a number of advantages over the conventionaldevices used to create lesions around pulmonary veins. For example, theoperative element carrying loops and the first and second curved membersmay be positioned around a pulmonary vein (or veins) on the epicardialsurface in accordance with inventive methods disclosed herein. Acontinuous transmural lesion that will isolate the vein may then becreated while the heart is beating. The heart need not be opened andpulmonary bypass is not required. As such, the present devicesadvantageously allow curative lesions to be formed around pulmonaryveins without the difficulties associated with catheter-based proceduresor the time on pulmonary bypass required by conventional surgicalprocedures.

In order to accomplish some of these and other objectives, a maskelement for masking an operative element supported on a support body inaccordance with a present invention includes a main body with a sidewall defining an interior bore and a side wall opening. The maskelement, which is preferably formed from thermally and electricallyinsulating material, is adapted to be positioned on the supportstructure such that a portion of the operative element is aligned withthe side wall opening and a portion of the operative element is coveredby the side wall. When the support structure is positioned with the sidewall opening (and exposed portion of the operative element) facing thetarget tissue region, the remainder of the operative element will becovered by the side wall. As such, the present mask element protectsnon-target collateral tissue from being damaged, sensed or otherwiseaffected by the operative element.

The above described and many other features and attendant advantages ofthe present inventions will become apparent as the inventions becomebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Detailed description of preferred embodiments of the inventions will bemade with reference to the accompanying drawings.

FIGS. 1A and 1B are partial plan views together showing a surgicaldevice in accordance with a preferred embodiment of a present invention.

FIG. 1C is a partial section view of the distal portion of the shaftillustrated in FIG. 1B.

FIG. 2 is a side view of the outer member illustrated in FIG. 1B.

FIG. 3 is an end view of the outer member illustrated in FIG. 1B.

FIG. 4 is a section view taken along line 44 in FIG. 1B.

FIG. 5 is a perspective view showing the surgical device illustrated inFIGS. 1A-1C being used in a surgical procedure involving the heart.

FIGS. 6A and 6B are partial plan views together showing a surgicaldevice in accordance with a preferred embodiment of a present invention.

FIG. 7A is a plan view of a portion of a surgical device in accordancewith a preferred embodiment of a present invention.

FIG. 7B is a partial section view of the distal portion of the shaftillustrated in FIG. 7A.

FIGS. 8A and 8B are partial plan views together showing a surgicaldevice in accordance with a preferred embodiment of a present invention.

FIG. 8C is a partial section view of the distal portion of the shaftillustrated in FIG. 8B.

FIG. 9A is a perspective view of the exemplary anchoring deviceillustrated in FIG. 8B.

FIGS. 9B-9D are perspective views of other exemplary anchoring devices.

FIG. 10 is a side, partial section view of a pull wire guide andelectrode support structure in accordance with a preferred embodiment ofa present invention.

FIG. 11 is a perspective view of the pull wire guide illustrated in FIG.10.

FIG. 12 is a perspective view of a pull wire guide in accordance with apreferred embodiment of a present invention.

FIGS. 13A and 13B are partial plan views together showing a surgicaldevice in accordance with a preferred embodiment of a present invention.

FIG. 14 is a plan view of a surgical device in accordance with apreferred embodiment of a present invention.

FIG. 15 is a section view taken along line 15—15 in FIG. 14.

FIG. 16 is a section view taken along line 16—16 in FIG. 14.

FIG. 17A is a partial side view of a distal structure that may be usedin conjunction with a surgical device such as that illustrated in FIGS.14 and 17C.

FIG. 17B is a side view of another distal structure that may be used inconjunction with a surgical device such as that illustrated in FIGS. 14and 17C.

FIG. 17C is a plan view of a surgical device in accordance with apreferred embodiment of a present invention.

FIG. 17D is a perspective view of a tip electrode in accordance with apreferred embodiment of a present invention.

FIG. 17E is a side view of the tip electrode illustrated in FIG. 17D.

FIG. 17F is a partial perspective view of another tip electrode.

FIG. 18 is a plan view showing a portion of a surgical device andelectrode identification system in accordance with a preferredembodiment of a present invention.

FIG. 19 is an exploded perspective view of a mask element in accordancewith a preferred embodiment of a present invention.

FIG. 20 is an exploded side view of the mask element illustrated in FIG.19 in combination with a surgical device that carries a plurality ofelectrodes.

FIG. 21 is a front plan view of a clamp device in accordance with apreferred embodiment of a present invention.

FIG. 22 is an enlarged rear plan view of a portion of the clamp deviceillustrated in FIG. 21.

FIG. 23 is a section view taken along line 23—23 in FIG. 21.

FIG. 24 is a section view taken along line 24—24 in FIG. 21.

FIG. 25 is a plan view of a clamp device in accordance with a preferredembodiment of a present invention.

FIG. 26 is a perspective view of a portion of a heart with lesionsformed in accordance with a therapeutic method in accordance with apresent invention.

FIG. 27 is a perspective view of a portion of a heart with a lesionformed in accordance with a therapeutic method in accordance with apresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is a detailed description of the best presently knownmodes of carrying out the inventions. This description is not to betaken in a limiting sense, but is made merely for the purpose ofillustrating the general principles of the inventions.

The detailed description of the preferred embodiments is organized asfollows:

I. Loop Structures With Coupling Devices

II. Loop Structures With Coupling Devices And Pull Wires

III. Loop Structures With Pull Wires

IV. Operative Elements, Temperature Sensing And Power Control

V. Operative Element Identification

VI. Masking

VII. Clamp Devices

VIII. Methods

The section titles and overall organization of the present detaileddescription are for the purpose of convenience only and are not intendedto limit the present inventions.

This specification discloses a number of structures, mainly in thecontext of cardiac ablation, because the structures are well suited foruse with myocardial tissue. Nevertheless, it should be appreciated thatthe structures are applicable for use in therapies involving other typesof soft tissue. For example, various aspects of the present inventionshave applications in procedures concerning other regions of the bodysuch as the prostate, liver, brain, gall bladder, uterus and other solidorgans.

I. Loop Structures With Coupling Devices

As illustrated for example in FIGS. 1A and 1B, a surgical device 10 inaccordance with a preferred embodiment of a present invention includes ashaft 12 that is preferably formed from two tubular parts, or members.The proximal member 14 is attached to a handle 16 while the distalmember 18, which is shorter than the proximal member, carries anoperative element such as the illustrated plurality of spaced electrodes20. The proximal member 14 is typically formed from a biocompatiblethermoplastic material that is thermally and electrically insulating,such as a Pebax® material (polyether block amide). The distal member 18is typically formed from a softer, more flexible biocompatiblethermoplastic material that is also thermally and electricallyinsulating, such as Pebax® material, polyethylene, or polyurethane. Theproximal and distal members, which are about 5 French to about 9 Frenchin diameter, are preferably either bonded together with an overlappingthermal bond or adhesively bonded together end to end over a sleeve inwhat is referred to as a “butt bond.”

The shaft 12 in the exemplary surgical device 10 extends through theinterior bore of an outer member 22 in the manner illustrated in FIGS.1A and 1B. The outer member 22 is preferably a tubular structure thatincludes a locking device 24, such as the illustrated Toughy Borstfitting, at the proximal end to fix the position of the shaft 12relative to the outer member. The outer member 22 also preferablyincludes a flared inner surface 23 (FIG. 2) to facilitate movement ofthe electrodes 20 into the outer member. Alternatively, the distal endof the outer member may be formed from relatively soft material. Withrespect to materials, the outer member 22 may be formed from a thermallyand electrically insulating -biocompatible thermoplastic material suchas Pebax® material.

The shaft 12 and outer member 22 are both relatively short. The term“relatively short” is used in the present specification to describe alength that is suitable for direct placement against the targeted tissueregion during a surgical procedure. “Relatively long” shafts, on theother hand, include conventional catheter shafts that are guided throughthe vasculature to a target tissue region. In the context of thesurgical procedures involving the heart, access to the targeted tissueregion may be obtained by way of a thoracotomy, median sternotomy, orthoracostomy. As such, the length of the shaft 12 is preferably betweenabout 6 inches and about 30 inches, with the proximal member 14 beingbetween about 3 inches and about 20 inches, and the distal member 18being between about 3 inches and about 20 inches. The length of theouter member 22 is only about 2 inches to about 10 inches.

A loop may be formed by securing the distal end of the shaft 12 to thedistal end of the outer member 22 and a fastening apparatus is providedthat allows the distal ends to be releasably secured to one another. Thefastening apparatus in the illustrated embodiment consists of a hook 26on the distal end of the outer member 22 and an eyelet 28 on the distalend of the shaft 12. Referring more specifically to FIGS. 2 and 3, thehook 26 is mounted on a cylindrical base 30 that is itself mounted onthe exterior of the distal end of the outer member 22. The base 30,which along with the hook 26 is preferably formed from metal or plastic,may be secured to the outer member 22 through the use of adhesive,welding or other suitable methods. The eyelet 28 is anchored to aflexible internal core wire 32 (FIG. 4) that may be formed fromresilient inert wire, such as stranded or solid nickel titanium(commercially available under the name Nitinol), braided Spectran® orKevlar® fibers, or common suture materials. Suitable materials for theeyelet 28 include Nitinol, 17-7 stainless steel, Spectran® and Kevlar®.It should also be noted that the locations of the hook 26 and eyelet 28may be reversed.

The core wire 32 is anchored at the proximal end of the shaft 12, whilethe core wire and eyelet 28 are both anchored at the distal end of theshaft. Referring to FIG. 1C, the proximal portion of the eyelet 28 andthe distal portion of the core wire 32 are secured to one another with acrimp tube 27 in the exemplary embodiment. The crimp tube 27 issoldered, welded or otherwise bonded to a tip anchor 29 that is mountedon the distal end of the distal member 18. An insulating sleeve 31 isalso provided along the length of the distal member 18.

Although the core wire 32 is preferably circular in cross-section, theportion of the core wire within the distal member 18 may have arectangular (or other non-circular shape) cross-section in order tocontrol the bending plane of the distal member. This technique isespecially useful when portions of the electrodes 20 are masked usingone of the techniques described in Section VI below.

As illustrated for example in FIG. 5, one use of the exemplary surgicaldevice 10 involves the creation of an epicardial lesion around a pair ofpulmonary veins PV. The shaft 12 and outer member 22 are directlyinserted into the patient's chest and the shaft distal member 18 may bethreaded around a pair of pulmonary veins PV with hemostats or othersurgical instruments. An adjustable loop 33 is formed by placing theeyelet 28 over the hook 26. The loop 33 may be tightened around thepulmonary veins PV by holding the outer member 22 and pulling the shaft12 in the proximal direction. Relative movement of the shaft 12 andouter member 22 can be prevented with the locking device 24 to maintainthe loop 33 in the desired size. Once the loop 33 has been accuratelypositioned, some or all of the electrodes 20 may be used to create atransmural epicardial lesion around the pulmonary veins PV. Additionalinformation concerning methods of creating epicardial lesions isprovided in Section VIII below.

In order to allow the distal member 18 to be tightly threaded around arelatively small structure such as a pulmonary vein, the distal memberis preferably very flexible. As used herein, the term “very flexible”refers to distal members which are more flexible than the distalportions of conventional diagnostic and steerable electrophysiologycatheters, which must be stiff enough to force electrodes againsttissue.

The exemplary handle 16 illustrated in FIG. 1A consists of two moldedhandle halves and is provided with strain relief element 36 and a PCboard 38. As discussed in greater detail in Section IV below, there is atemperature sensor associated with each longitudinal edge of theelectrodes 20 in the illustrated embodiment. Signal wires 41 (FIG. 4)are connected to the electrodes 20 and signal wires 42 are connected tothe temperature sensors. The signal wires are passed in conventionalfashion through a lumen extending through the shaft 12 to the PC board38. The PC board 38 is, in turn, electrically coupled to a connectorthat is received in a port at the proximal end of the handle 16. Theconnector plugs into a source of RF coagulation energy.

Another exemplary device, which is generally represented by referencenumeral 40, is illustrated in FIGS. 6A and 6B. Many structural elementsin the exemplary device 40 are similar to those in the exemplary device10 and such elements are represented by the same reference numerals. Forexample, the exemplary device 40 includes a relatively short shaft 12with a proximal member 14 and a distal member 18 that supports aplurality of electrodes 20 or some other operative element. Exemplarydevice 40 also includes a handle 16 and a hook 26 and eyelet 28arrangement.

The primary difference between the two surgical devices is that theexemplary device 40 includes a relatively short outer member 42 that isrelatively stiff. In other words, the outer member is either rigid,malleable, or somewhat flexible. A rigid outer member cannot be bent. Amalleable outer member is a outer member that can be readily bent by thephysician to a desired shape, without springing back when released, sothat it will remain in that shape during the surgical procedure. Thus,the stiffness of a malleable outer member must be low enough to allowthe outer member to be bent, but high enough to resist bending when theforces associated with a surgical procedure are applied to the outermember. A somewhat flexible outer member will bend and spring back whenreleased. However, the force required to bend the outer member must besubstantial. Rigid and somewhat flexible shafts are preferably formedfrom stainless steel, while malleable shafts are formed from annealedstainless steel. Additional information concerning malleable structuresmay be found in aforementioned U.S. application Ser. No. 09/072,872.

A rigid or somewhat flexible outer member 42 may be linear or formedwith one or more bends 44 designed for a particular surgical procedure,as is illustrated for example in FIG. 6B. The physician may place bendsin a malleable outer member 42 in order to facilitate proper placementof the distal end of the outer member.

II. Loop Structures With Coupling Devices and Pull Wires

It may be difficult in some instances to thread the shaft distal member18 around an anatomical structure such as a pulmonary vein. As such, thedistal end of the shaft 12 may be provided with a pull wire 34, as isillustrated for example FIG. 7A. The pull wire 34, which is thinner andmore flexible than the shaft distal member 18, will be easier to threadaround anatomical structures. After the pull wire 34 has been threadedaround a pulmonary vein or other structure, and around the hook 26, thepull wire may be used to pull the shaft distal member 18 around thestructure to form a loop. Suitable materials for the pull wire 34, whichis typically more flexible than the core wire 32, include strandedNitinol, Spectran® and Kevlar®.

The pull wire 34 may be secured to the core wire 32 with a crimp tube orother suitable device in the manner illustrated, for example, in FIG.7B. More specifically, the proximal portions of the eyelet 28 and pullwire 34 and the distal portion of the core wire 32 are secured to oneanother with a crimp tube 27. The crimp tube 27 is soldered, welded orotherwise bonded to a tip anchor 29 that is mounted on the distal end ofthe distal member 18.

III. Loop Structures With Pull Wires

As illustrated for example in FIGS. 8A and 8B, a surgical device 46 inaccordance with a preferred embodiment of a present invention includesmany structural elements similar to those in the exemplary devicesillustrated in FIGS. 1A-7B and such elements are represented by the samereference numerals. For example, the exemplary surgical device 46includes a relatively short shaft 12 with a proximal member 14 and adistal member 18 that supports a plurality of electrodes 20 or someother operative element. The proximal end of the shaft 12 is secured toa handle 16.

As illustrated for example in FIG. 8C, a pull wire 34 similar to thatillustrated in FIGS. 7A and 7B is crimped to the core wire 32 with acrimp tube 27 and the crimp tube is secured to a tip anchor 29′ bybonding, welding or other suitable methods. Here, however, the tipanchor 29′ has a closed distal end and the pull wire 34 is threadedthrough an opening 33 in the anchor. Alternatively, the core wire 32 andpull wire 34 may be replaced with a single, continuous pull/core wire(not shown).

The exemplary surgical device 46 does not, however, include an outermember with a coupling device that secures the distal portion of theouter member to the shaft distal member 18. Instead, surgical device 46includes a relatively short outer member 48 with a pull wire guide 50.The outer member 48 also includes a flared inner surface (not shown) orsoft material at its distal end and a locking device 24, such as aToughy Borst fitting, at its proximal end to fix the position of theshaft 12. The pull wire 34 may be threaded through the pull wire guide50 to form a loop 51 and then secured to an anchoring device 52. Theloop 51 may then be adjusted by moving the shaft 12 and outer member 48relative to one another or by adjusting the pull wire, 34. In oneexemplary procedure, the pull wire 34 will be threaded around a pair ofpulmonary veins prior to being threaded through the pull wire guide 50to form a loop similar to that illustrated in FIG. 5.

With respect to the physical characteristics of the outer member 48, theouter member is preferably formed from relatively high durometermaterials (72D and above) such as braided or unbraided Pebax® or Nylonmaterial that is stiffer than the distal member 18 as well as thermallyand electrically insulating. The outer member 48 should also be slightlyshorter (i.e. 1 to 2 inches shorter) than the proximal member 14.

As illustrated in FIGS. 8B and 9A, the exemplary anchoring device 52includes a main body 54 that is mounted on the outer member 48, a post56 and a cap 58. The cap 58 includes a pair of slots 60. The pull wire34 is wound around the post 56 and then through the slots 60 to anchorit in place. The anchoring device 52 is preferably formed from moldedplastic. An alternate anchoring device 52′, with a slightly differentlyshaped cap 58′, is illustrated in FIG. 9B. Still other anchoringdevices, which are represented by reference numerals 53 and 53′, areillustrated in FIGS. 9C and 9D. Here, slots 55 extend through caps 57and 57′ and into the posts 56 on which the caps are mounted. Theflexibility of the plastic material allows the pull wire 34 to be pulleddown through into slot 55 and then held in place through friction andmechanical interference.

In the exemplary embodiment illustrated in FIGS. 8A-8C, the pull wireguide 50 is an eyelet or other simple loop or hook structure formed frommetal or plastic that is mounted on a cylindrical base 62.Alternatively, as illustrated in FIGS. 10 and 11, a pull wire guide 64may be provided with a plurality of pull wire openings 66 that extendaround the periphery of the distal end of the outer member 48. Thisarrangement facilitates the threading of a pull wire through the pullwire guide 64 regardless of the rotational orientation of the outermember 48 relative to the physician and patient and also eliminates theneed for the rotational orientation to be closely monitored and/oradjusted prior to loop formation.

The exemplary pull wire guide 64 illustrated in FIGS. 10 and 11, whichmay be formed from metal or plastic, includes a base 68 and an outwardlyflared member 70 in which the openings 66 are located. The base 68 has amounting surface 72 with a shape corresponding to that of the outermember on which it is mounted, i.e. cylindrical in the illustratedembodiment, and a smooth curved lip 74 that should extend inwardly fromthe mounting surface a distance that is at least equal to the wallthickness of the outer member. The flared member 70 includes a pluralityof supports 75 and a peripheral ring 76 that together define the pullwire openings 66. The flared member 70 also has a smooth inner surface78 that, together with the smooth curved lip 74, facilitates movement ofthe electrodes 20 or other operative elements through the pull wireguide 64 and into the outer member 48.

Turning to FIG. 12, the exemplary pull wire guide 80 illustrated thereinis substantially similar to the guide illustrated in FIGS. 10 and 11 andsimilar structural elements are represented by similar referencenumerals. Here, however, the peripheral ring 76 in the flared member 70has been replaced by a plurality of a peripheral members 82 in a flaredmember 70′ that define slots 84 therebetween. The slots 84 allow a pullwire to be slipped into the openings 66 instead of threaded through theopenings. The peripheral members 82 also include curved, inwardlyextending end portions 86 that prevent the pull wire from sliding out ofthe openings 66 once it is located therein.

Another exemplary surgical device, which is generally represented byreference numeral 88, is illustrated in FIGS. 13A and 13B. Like theexemplary surgical device 46 illustrated in FIGS. 8A-8C, surgical device88 includes a shaft 12, with a proximal member 14 secured to handle 16and a distal member 18 that supports electrodes 20 or some otheroperative element, and a pull wire 34. However, instead of a singlerelatively short outer member, surgical device 88 includes an outermember assembly 90 with a pair of outer members 92 and 94. A loop 95 isformed by directing the shaft distal member 18 outwardly from the distalend of outer member 92 and into the distal end of the outer member 94.The pull wire 34 may be anchored with an anchoring member 52 and theshaft 12 held in place relative to the outer member 92 with a lockingdevice 24. The outer members are preferably formed from stainless steelor molded polymer material and have a inner diameter of about 7 Frenchand an outer diameter of about 10 French.

The configuration of the loop 95 formed by the distal member 18 isprimarily determined by the shape and relative orientation of the outermembers 92 and 94. In the illustrated embodiment, outer member 92 islinear and outer member 94 is curved. The outer members 92 and 94, whichare held in place relative to one another by a post 96 and weld (notshown) in region 98, are oriented such that the distal ends thereofdefine an angle of about 45 degrees. Of course, the curvatures of theouter members 92 and 94, as well as the relative orientation thereof,may be adjusted to suit particular needs.

In order to facilitate formation and adjustment of the loop 95, outermember 94 includes a pull wire slot 100 and the distal ends of the outermembers 92 and 94 respectively include outwardly flared portions 102 and104. The pull wire slot 100 is wide enough to allow the pull wire 34 toslide into the outer member 94, yet too narrow to allow the shaft distalmember 18 to slide out of the outer member once it has been pulled in.As such, loop 95 may be formed by advancing the shaft distal member 18outwardly from the distal end of the outer member 92, pulling on thepull wire 34 to bend the distal member back in the proximal direction,sliding the pull wire into the pull wire slot 100, and pulling thedistal member into the distal end of the outer member 94.

As illustrated for example in FIGS. 14-16, a surgical device 106 inaccordance with another preferred embodiment includes a relatively shortshaft 108, a handle 16, and a distal section 110. The shaft 108 consistsof a hypo-tube 112, which is either rigid or relatively stiff(preferably malleable), and an outer polymer tubing 114 over thehypo-tube. The distal section 110 is preferably somewhat flexible, inthat it will conform to a surface against which it is pressed and thenspring back to its original shape when removed from the surface.Surgical device 106 also includes a pull wire 34. The pull wire 34 ispre-threaded between the hypo-tube 112 and outer tubing 114 and throughan aperture in the handle. Alternatively, the pull wire 34 may bethreaded through a pull wire guide in the manner described above.

Referring more specifically to FIGS. 15 and 16, the exemplary distalsection 110 preferably includes a spring member 116, which is preferablyeither a solid flat wire spring (as shown), a round wire, or a threeleaf flat wire Nitinol spring, that is connected to the distal end ofthe hypo-tube 112 by welding or a crimp tube. Other spring members,formed from materials such as 17-7 or carpenter's steel, may also beused. As noted above, signal wires 41 and 42 connect the electrode 20and temperature sensor elements to the PC board 38. The spring member116 and signal wires 41 and 42 are enclosed in a flexible body 118,preferably formed from Pebax® material, polyurethane, or other suitablematerials. The spring member 116 may also be pre-stressed so that thedistal tip is pre-bent. An insulating sleeve 120 may be placed betweenthe spring member 116 and the lead wires 41 and 42 if desired.

The distal section 110 may, alternatively, have a malleable portion. Asillustrated for example in FIG. 17A, the spring member 116 (FIG. 16) isreplaced with a shorter, but otherwise identical spring member 116′ anda tapered malleable member 122 that is secured to the hypotube 112 bywelding or other suitable methods. In a preferred implementation havingseven electrodes, the malleable member 122 will extend to fourthelectrode (counting proximal to distal), although this may be varieddepending on the intended application. The spring member 116′ andmalleable member 122 may be secured to one another with a stainlesssteel crimp tube 124, which is soldered or otherwise bonded to themalleable member and mechanically coupled to the spring member withcrimps 126. Suitable materials for the malleable member 122 includestainless steel.

The malleable portion within the distal section 110 may also be providedin the manner illustrated in FIG. 17B. Here, the spring member 116′ issecured to malleable hypotube 121 with, for example, crimps 123. Thehypotube 121 is secured to the hypotube 112 by welding or other suitablemethods. One particular advantage of this arrangement is that therelative lengths of the malleable and flexible regions may be variedduring manufacture by simply varying the length of the hypotube 121.

Probes having distal sections with both malleable and flexible regionsmay also be provided without a pull wire. The exemplary probe 106′illustrated in FIG. 17C is essentially identical to the probe 106illustrated in FIG. 14. Here, however, the pull wire 34 and outer tubing114 have been eliminated and a tip electrode 125 has been added.

Referring to FIGS. 17D and 17E, the tip electrode 125 preferablyincludes a through hole 127 that allows instrumentalities, such assuture material or one-quarter inch umbilical tape, to be threadedthrough the electrode to form a pull wire-like device if desired. Thethrough hole 127 may also be engaged by a towel clamp formed fromnon-conducting material, or other similar device, during a procedure toallow the physician to push or pull from either end of the probe 106′for positioning and pressure application purposes. For example, afterthe suture material has been used to pull the probe 106′ around an organsuch as the heart, a towel clamp may be used to grab the distal end ofthe probe for more accurate positioning.

The ends of the through hole 127 are preferably chamfered and, asillustrated in FIG. 17E, the through hole may extend straight throughthe tip electrode 125. Alternatively, as illustrated in FIG. 17F,electrode 125′ includes a through hole 127′ with two portions arrangedat an angle to one another. A lumen 129, having a large diameter portionand a small diameter portion (in which temperature sensors may belocated), extends through the base 131 and into the interior of the tipelectrode 125. The base 131 is inserted into the end of the distalsection 110 during assembly.

It should be noted that a tip electrode with a through hole, such asthose illustrated in FIGS. 17D-17F, may be used in combination withother probes, including those illustrated in FIGS. 1-13 of the presentapplication. The exemplary electrodes illustrated in FIGS. 17C-17F havean outer diameter of about 2.7 mm and are about 8 mm in length. The sizeand shape of the tip electrode may, of course, be varied as desired tosuit particular applications.

There are a number of advantages associated with probes having a distalsection with both malleable and flexible regions. For example, thecombination of malleable and flexible regions in the distal section 110allows a single probe to form a wide variety of lesions. The relativelystiff, malleable region of the distal section 110 may be shaped toconform to anatomical structures on, for example, the surface of theheart. Direct pressure may then be applied to the structure during theformation of continuous lesions (note lesion 152 in FIG. 26) orsegmented lesion patterns. The flexible region of the distal section 110may be wrapped around anatomical structures such as, for example,pulmonary veins (note lesions 202 and 204 in FIG. 26). The malleable andflexible regions may also be used in conjunction with one another by,for example, shaping the malleable region to suit a particular procedureprior to wrapping the flexible region around an anatomical structure.

A probe with a combination of malleable and flexible regions in thedistal section 110 may also be used in combination with the relativelyshort outer member 48 illustrated in FIG. 8B.

IV. Operative Elements, Temperature Sensing And Power Control

In each of the preferred embodiments, the operative element is aplurality of spaced electrodes 20. However, other operative elements,such as lumens for chemical ablation, laser arrays, ultrasonictransducers, microwave electrodes, and ohmically heated hot wires, andthe like may be substituted for the electrodes.

The spaced electrodes 20 are preferably in the form of wound, spiralcoils. The coils are made of electrically conducting material, likecopper alloy, platinum, or stainless steel, or compositions such asdrawn-filled tubing (e.g. a copper core with a platinum jacket). Theelectrically conducting material of the coils can be further coated withplatinum-iridium or gold to improve its conduction properties andbiocompatibility. A preferred coil electrode is disclosed in U.S. Pat.No. 5,797,905.

As an alternative, the electrodes may be in the form of solid rings ofconductive material, like platinum, or can comprise a conductivematerial, like platinum-iridium or gold, coated upon the device usingconventional coating techniques or an ion beam assisted deposition(IBAD) process. For better adherence, an undercoating of nickel,. silveror titanium can be applied. The electrodes can also be in the form ofhelical ribbons. The electrodes can also be formed with a conductive inkcompound that is pad printed onto a non-conductive tubular body. Apreferred conductive ink compound is a silver-based flexible adhesiveconductive ink (polyurethane binder), however other metal-based adhesiveconductive inks such as platinum-based, gold-based, copper-based, etc.,may also be used to form electrodes. Such inks are more flexible thanepoxy-based inks.

The flexible electrodes 20 are preferably about 4 mm to about 20 mm inlength. In the preferred embodiment, the electrodes are 12.5 mm inlength with 1 mm to 3 mm spacing, which will result in the creation ofcontinuous lesion patterns in tissue when coagulation energy is appliedsimultaneously to adjacent electrodes. For rigid electrodes, the lengthof the each electrode can vary from about 2 mm to about 10 mm. Usingmultiple rigid electrodes longer than about 10 mm each adversely effectsthe overall flexibility of the device, while electrodes having lengthsof less than about 2 mm do not consistently form the desired continuouslesion patterns.

The electrodes 20 may be operated in a uni-polar mode, in which the softtissue coagulation energy emitted by the electrodes is returned throughan indifferent patch electrode (not shown) externally attached to theskin of the patient. Alternatively, the electrodes may be operated in abi-polar mode, in which energy emitted by one or more electrodes isreturned through other electrodes. The amount of power required tocoagulate tissue ranges from 5 to 150 w.

As illustrated for example in FIG. 10, a plurality of temperaturesensors 128, such as thermocouples or thermistors, may be located on,under, abutting the longitudinal end edges of, or in between, theelectrodes 20. Preferably, the temperature sensors 128 are located atthe longitudinal edges of the electrodes 20 on the side of the structureintended to face the tissue. In some embodiments, a referencethermocouple 130 (FIG. 14) may also be provided. For temperature controlpurposes, signals from the temperature sensors are transmitted to thesource of coagulation energy by way of wires 42 (FIG. 4) that are alsoconnected to the aforementioned PC board 38 in the catheter handle.Suitable temperature sensors and controllers which control power toelectrodes based on a sensed temperature are disclosed in U.S. Pat. Nos.5,456,682, 5,582,609 and 5,755,715.

The temperature sensors are also preferably located within a linearchannel (not shown) that is formed in the distal member. The linearchannel insures that the temperature sensors will directly face thetissue and be arranged in linear fashion. The illustrated arrangementresults in more accurate temperature readings which, in turn, results inbetter temperature control. As such, the actual tissue temperature willmore accurately correspond to the temperature set by the physician onthe power control device, thereby providing the physician with bettercontrol of the lesion creation process and reducing the likelihood thatembolic materials will be formed. Such a channel may be employed inconjunction with any of the electrode (or other operative element)supporting structures disclosed herein.

Finally, the electrodes 20 and temperature sensors 128 can include aporous material coating, which transmits coagulation energy through anelectrified ionic medium. For example, as disclosed in U.S. Pat. No.5,991,650, electrodes and temperature sensors may be coated withregenerated cellulose, hydrogel or plastic having electricallyconductive components. With respect to regenerated cellulose and othermicro-porous materials, the coating acts as a mechanical barrier betweenthe surgical device components, such as electrodes, preventing ingressof blood cells, infectious agents, such as viruses and bacteria, andlarge biological molecules such as proteins, while providing electricalcontact to the human body. The micro-porous material coating also actsas a biocompatible barrier between the device components and the humanbody, whereby the components can now be made from materials that aresomewhat toxic (such as silver or copper).

V. Operative Element Identification

Certain power source and control devices, such as the Cobra®electrosurgical unit manufactured by EP Technologies, Inc., allow thephysician to individually select which of the electrodes 20 will besupplied with power. In a seven electrode arrangement, for example, thepower supply and control device will include seven on-off switches thatrespectively correspond to the seven electrodes 20. Such an arrangementallows the physician to selectively enable only those electrodes that,for example, are located outside the outer member 22 after a loop hasbeen formed around an anatomical structure. Nevertheless, it can bedifficult for the physician to accurately determine how many of theelectrodes are outside the outer member 22 during a surgical procedurewhere the physician makes use of a direct line of sight into the patientbecause some of the electrodes may be located behind the anatomicalstructure.

An electrode identification system in accordance with a presentinvention may be provided to enable the physician to readily determinehow many of the electrodes are located outside of an outer member. Theidentification system, one embodiment of which is illustrated in FIG.18, includes indicia associated with the electrodes and correspondingindicia on the outer member. More specifically, the illustratedembodiment includes unique indicia (i.e. the indicia that are visuallydistinguishable from one another) 130 a, 132 a and 134 a on the distalmember 18, each of which corresponds to a particular one of theproximal-most three of the seven electrodes 20, and correspondingindicia 130 b, 132 b and 134 b on the distal portion of the outer member22. The exemplary indicia is in the form of colored rings or bands.Indicia 130 a and 130 b are black, indicia 132 a and 132 b are red, andindicia 134 a and 134 b are blue. The order of the indicia (i.e. black,red, blue) is the same on the distal member 18 and outer member 22.

The indicia is used by the physician in the following manner. When aloop is formed around pulmonary veins in the manner illustrated in FIG.5, a number of electrodes 20 will be located behind the pulmonary veins(from the physicians perspective) and one of the electrodes will belocated immediately adjacent the distal end of the outer member 22. If,for example, the indicia associated with the electrode 20 adjacent thedistal end of the outer member 22 is the blue indicia 134 a, thephysician will know by reviewing the indicia on the distal end of theouter member that there are two electrodes proximal to the “blue”electrode (i.e. the electrode associated with the red indicia 132 b andthe electrode associated with the black indicia 130 b). Given the factthat two of the electrodes 20 are located within the outer member 22,the physician will be able to determine that the distal-most fiveelectrodes are in contact with tissue, despite the fact that one or moreof the five electrodes is not visible by direct observation because theyare behind the pulmonary veins.

The number of electrodes that have indicia associated therewith, as wellas the percentage of the total number electrodes that have indiciaassociated therewith, will depend on the particular surgical procedurefor which the identification system is intended. Other visible indicia,such as alpha-numeric symbols or shading, may also be employed.Additionally, although the embodiment of the system illustrated in FIG.18 is shown in combination with the surgical device illustrated in FIGS.1A and 1B, other devices, such as those disclosed in the presentspecification, may also be provided with such a system.

VI. Masking

The portion of an operative element that is not intended to contacttissue (or be exposed to the blood pool) may be masked through a varietyof techniques with a material that is preferably electrically andthermally insulating. This prevents the transmission of coagulationenergy directly into the blood pool and directs the energy directlytoward and into the tissue. This also prevents collateral damage totissue by blocking transmission of coagulation energy into adjacent,non-target tissue. In the context of epicardial lesion creation, suchnon-target tissue may include the phrenic nerve and lung tissue.

For example, a layer of UV adhesive (or another adhesive) may be paintedon preselected portions of the electrodes to insulate the portions ofthe electrodes not intended to contact tissue. Deposition techniques mayalso be implemented to position a conductive surface only on thoseportions of the assembly intended to contact tissue. A coating may alsobe formed by dipping the electrodes in PTFE material.

Alternatively, a mask element may be positioned over a structure thatsupports one or more electrodes or other operative element toelectrically and thermally insulate the desired portions thereof. Asillustrated for example in FIGS. 19 and 20, a mask element 136 inaccordance with one embodiment of a present invention includes a mainbody 138, having a side wall 140 defining an interior bore 142 and aplurality of openings 144, and a plurality of fluid retention elements146 located in the openings. The main body 138 is preferably formed frommaterial that is electrically and thermally insulating. The fluidretention elements 146 may be used to retain a conductive liquid such assaline and release the liquid during diagnostic or therapeuticprocedures. When, for example, the mask element 136 is placed over theexemplary distal member 18, coagulation energy from the electrodes 20will only be transmitted through the openings 144.

With respect to materials, the main body 138 is preferably formed froman elastic material that will hold the mask element 136 on the distalmember 18 or other operative element supporting structure, yet alsoallow the surgeon to rotate the main body to focus the coagulationenergy, or remove the mask element altogether, as desired. A suitableelastic material is silicone rubber having a thickness that ranges fromabout 0.05 mm to about 1 mm, depending on the desired level ofinsulation. For some surgical devices, the main body 138 need only bebendable, as opposed to elastic. Here, biocompatible plastics that arecommonly used in catheters, such as Pebax® material and polyurethane,may be employed and the main body 138 secured to the surgical devicewith an adhesive.

Suitable materials for the fluid retention elements 146 includebiocompatible fabrics commonly used for vascular patches (such as wovenDacron®), open cell foam materials, hydrogels, macroporous balloonmaterials (with very slow fluid delivery to the surface), andhydrophilic microporous materials. The effective electrical resistivityof the fluid retention elements 146 when wetted with 0.9% saline (normalsaline) should range from about 1 Ω-cm to about 2000 Ω-cm.

Because it is important that the physician be able to identify theelectrodes 20 or other operative elements that are in contact withtissue, the exemplary main body 138 should either be transparent or beprovided with indicia (not shown) that allows the physician todistinguish between the electrodes. Such indicia, which may be printeddirectly onto the main body 138 with biocompatible ink, includes colorcoding, alpha-numeric indicia and shading.

Mask elements in accordance with the present invention may be used inconjunction with devices other that the shaft and spaced closed coilelectrode structure illustrated in FIG. 20. For example, the closed coilelectrodes may be replaced with open coil electrodes or a straight pieceof wire. Also, temperature sensors may be moved from the underlyingsupport structure to a portion of the mask element, preferably to thefluid retention elements. The temperature sensors could be woven intofabric fluid retention material or embedded in fluid retention elementsformed from other materials. Here, however, rotational movement of themask element should be limited to, for example, 180 degrees in order toprevent damage to the signal wires that will be connected to thetemperature sensors.

VII. Clamp Devices

As illustrated for example in FIGS. 21-24, a clamp device 148 inaccordance with a preferred embodiment of a present invention includes aforceps-like apparatus 150 and a tissue coagulation apparatus 152. Theforceps-like apparatus 150 includes arms 154 and 156 that are pivotablysecured to one another by a pin 158 to allow the device to be opened andclosed. The proximal portions of the arms 154 and 156 may be formed fromrigid or malleable material. The arm distal portions 160 and 162, whichare curved and support the tissue coagulation apparatus 152, arepreferably formed from malleable material. This allows the arm distalportions 160 and 162 to be re-shaped by the physician as needed forparticular procedures and body structures (note the dash lines in FIG.21). Alternatively, one or both of the arm distal portions 160 and 162may be formed from rigid material. The arm distal portions 160 and 162and, preferably the entire forceps-like apparatus 150, will be coatedwith a layer of insulating material (not shown), such as heat shrinkPebax® material, polyester, or polyurethane. A pair of handles 164 and166 are mounted on the proximal ends of the arms 154 and 156.

The exemplary tissue coagulation apparatus 152 includes an operativeelement support member 168 that may be formed from a soft, flexible,insulative, biocompatible thermoplastic material such as Pebax®material, polyethylene, or polyurethane. In the illustrated embodiment,which may be used to form lesions around one or more pulmonary veins,the operative element support member 168 will preferably be about 5French to about 9 French in diameter.

Referring more specifically to FIG. 21, the operative element supportmember 168 is a continuous structure, but for the break at the distalend of the arm distal portions 160 and 162 that allows the device to beopened and closed, which will form a continuous loop around a bodystructure when the clamp device is in the closed position illustrated inFIG. 21. As such, the electrodes 20 (or other operative element)supported thereon may be used to create a continuous lesion pattern intissue when coagulation energy is applied simultaneously to theelectrodes. Additionally, the curvature of the arm distal portions 160and 162 and operative element support member 168 allow the physician toapply pressure to a body structure, such as a pulmonary vein, that isadequate to enable the formation of a single continuous transmurallesion all the way around the body structure in one step withoutcollapsing the body structure, as would be the case with a device havingstraight arm distal portions. The open region defined by the arm distalportions 160 and 162 and operative element support member 168 may besubstantially circular, oval or any other closed shaped necessary for aparticular procedure.

The operative element support member 168 is preferably mounted offcenter by an angle θ on the arm distal portions 160 and 162, as bestseen in FIG. 24. In the illustrated embodiment, the operative elementsupport member 168 is approximately 45 degrees off center. Suchpositioning provides a number of advantages. For example, the off centerpositioning focuses the coagulation energy downwardly (towards theheart) and inwardly (towards the pulmonary veins) when the tissuecoagulation apparatus 152 is positioned around one or more pulmonaryveins. So positioned, with side A advanced against heart tissue, theinsulated arm distal portions 160 and 162 act as a shield to prevent thecoagulation of tissue other than that targeted for coagulation.Moreover, the physicians view of the tissue in contact with the tissuecoagulation apparatus 152 will not be blocked by the arm distal portions160 and 162.

As illustrated for example in FIGS. 21-23, an electrical conduit 170connects the tissue coagulation apparatus 152 to an electrical connector172 that may be connected to a source of RF coagulation energy. Morespecifically, signal wires 41 and 42 from the electrodes and temperaturesensors on the tissue coagulation apparatus 152 run through theelectrical conduit 170 along the arm 156 to the electrical connector172.

Another exemplary clamp device, which is generally represented byreference numeral 174, is illustrated in FIG. 25. Like the exemplaryclamp device illustrated in FIGS. 21-24, clamp device 174 includes aforceps-like device 176 and a tissue coagulation apparatus 178 which,unless otherwise indicated, are essentially the same as the forceps-likedevice and tissue coagulation apparatus illustrated in FIGS. 21-24.Here, however, the proximal ends of the arms 180 and 182 are pivotablysecured to one another by a pin 184 and the handles 186 and 188 arelocated just proximally of the pin. Also, given the distance that thecurved arm distal portions 190 and 192 are capable of moving from oneanother, the tissue coagulation apparatus 178 includes a pair ofoperative element support members 194 and 196 that are connected to theconnector 172 by a pair of electrical conduits 198 and 200.

It should also be noted that the although the exemplary clamp devicesillustrated above employ a forceps-like apparatus having a pair of armsconnected by a pivot pin to position the tissue coagulation apparatusaround tissue, other apparatus may also be employed. For example, anelongate apparatus including a scissors-like handle at one end, curveddistal portions at the other end, and a suitable mechanical linkagejoining the two may be employed.

VIII. Methods

In accordance with an invention herein, surgical devices such as thosedescribe above may be used to support an operative element on the outersurfaces of body structures for diagnostic and/or therapeutic purposes.In the context of the treatment of atrial fibrillation, for example,surgical devices with loop structures such as those described above maybe used to support an operative element, such as a plurality of spacedelectrodes, that creates transmural epicardial lesions to isolate thesources of focal (or ectopic) atrial fibrillation.

Turning to FIG. 26, an exemplary method of treating focal atrialfibrillation with a device such as that illustrated in FIG. 5 involvesthe creation of transmural lesions around the pulmonary veins. Lesionsmay be created around the pulmonary veins individually or, as isillustrated in FIG. 26, a first transmural epicardial lesion 202 may becreated around the right pulmonary vein pair RPV and a second transmuralepicardial lesion 204 may be created around the left pulmonary vein pairLPV. Thereafter, if needed, a linear transmural epicardial lesion 206may be created between the right and left pulmonary vein pairs RPV andLPV. A linear transmural lesion (not shown) that extends from theepicardial lesion 204 to the left atrial appendage may also be formed.The linear lesions may be formed with the probe described above withreference to FIGS. 17A and 17C. Other suitable surgical devices forcreating linear lesions, one example of which would be the deviceillustrated in FIGS. 14-16 without the pull wire, are disclosed inaforementioned U.S. application Ser. No. 09/072,872.

Alternatively, as illustrated in FIG. 27, a single lesion 208 may beformed around all four of the pulmonary vein pairs RPV and LPV.

Access to the heart may be obtained via a thoracotomy, thoracostomy ormedian sternotomy. Ports may also be provided for cameras and otherinstruments.

Surgical devices with loop structures such as those described above mayalso be used to create transmural epicardial lesions in a maze patternthat controls electrical propagation within the left and right atria.More specifically, a maze pattern may be created by positioning aplurality of spaced electrodes, or other operative element, within thepericardial space around the exterior of the heart at the variouslocations needed to form the desired lesion pattern.

The surgical devices described above may also be urged through tissueplanes (i.e. the space between fascia material and a particular organ)to properly position the device prior to the actuation of the operativeelements. Such a procedure is referred to as blunt dissection.

The clamp devices illustrated in FIGS. 21-25 may also be used to formlesions such as pulmonary vein lesions 202, 204 and 208, or lesionsaround other body structures.

Although the present inventions have been described in terms of thepreferred embodiments above, numerous modifications and/or additions tothe above-described preferred embodiments would be readily apparent toone skilled in the art. It is intended that the scope of the presentinventions extend to all such modifications and/or additions and thatthe scope of the present inventions is limited solely by the claims setforth below.

We claim:
 1. A method of creating an epicardial lesion, comprising thesteps of: positioning a closed loop structure including an operativeelement around a portion of the epicardium by positioning a first loopstructure member defining a distal portion adjacent to the epicardium,positioning a second loop structure member defining a distal portionadjacent to the epicardium with the distal portion of the second loopstructure member disconnected from the distal portion of the first loopstructure member without any physical structures extending beyond thedistal portion of the first loop structure member to the distal portionof the second loop structure member, and connecting the distal portionof the second loop structure member to the distal portion of the firstloop structure member to form the closed loop structure; tightening theclosed loop structure around the portion of the epicardium after theclosed loop structure has been formed; and actuating the operativeelement to create a lesion.
 2. A method as claimed in claim 1, whereinthe step of positioning a closed loop structure comprises positioning aclosed loop structure including a plurality of spaced electrodes aroundthe epicardium.
 3. A method as claimed in claim 1, wherein the step ofpositioning a closed loop structure comprises positioning a closed loopstructure around at least one pulmonary vein.
 4. A method as claimed inclaim 1, wherein the step of positioning a closed loop structurecomprises positioning a closed loop structure around a pair of pulmonaryveins.
 5. A method as claimed in claim 1, wherein the step of actuatingthe operative element to create a lesion comprises actuating theoperative element to create a transmural lesion.
 6. A method as claimedin claim 1, wherein the step of positioning the second loop structuremember comprises passing at least a portion of the second loop structuremember through the first loop structure member.
 7. A method as claimedin claim 1, wherein the step of connecting the distal portion of thesecond loop structure member to the distal portion of the first loopstructure member comprises fastening the distal portion of the secondloop structure member to the distal portion of the first loop structuremember.
 8. A method as claimed in claim 1, wherein the step ofconnecting the distal portion of the second loop structure member to thedistal portion of the first loop structure member comprises passing apull wire through a pull wire guide.
 9. A method as claimed in claim 1,wherein the step of tightening the loop structure comprises moving thesecond loop structure member proximally.
 10. A method of treating focalatrial fibrillation, comprising the steps of: positioning a closed loopstructure including an operative element on the epicardial surfacearound at least one pulmonary vein by positioning a first loop structuremember defining a distal portion adjacent to the epicardium, positioninga second loop structure member defining a distal portion adjacent to theepicardium with the distal portion of the second loop structure memberdisconnected from the distal portion of the first loop structure member,and connecting the distal portion of the second loop structure member tothe distal portion of the first loop structure member to form the closedloop structure; tightening the closed loop structure around the at leastone pulmonary vein after the closed loop structure has been formed; andcreating a lesion with the operative element that extends around the atleast one pulmonary vein.
 11. A method as claimed in claim 10, whereinthe step of creating a lesion with the operative element comprisescreating a transmural lesion with the operative element.
 12. A method asclaimed in claim 10, wherein the step of creating a lesion with theoperative element comprises creating a continuous lesion with theoperative element.
 13. A method as claimed in claim 11, wherein the stepof positioning a closed loop structure comprises positioning a closedloop structure including a plurality of spaced electrodes on theepicardial surface around the at least one pulmonary vein.
 14. A methodas claimed in claim 11, wherein the step of positioning a closed loopstructure comprises positioning a closed loop structure around a firstpair of pulmonary veins and the step of creating a lesion comprisescreating a first lesion with the operative element that extends aroundthe first pair of pulmonary veins.
 15. A method as claimed in claim 14,further comprising the steps of: positioning the closed loop structurearound a second pair of pulmonary veins; and creating a second lesionwith the operative element that extends around the second pair ofpulmonary veins.
 16. A method as claimed in claim 10, wherein the stepof positioning the second loop structure member comprises passing atleast a portion of the second loop structure member through the firstloop structure member.
 17. A method as claimed in claim 10, wherein thestep of connecting the distal portion of the second loop structuremember to the distal portion of the first loop structure membercomprises fastening the distal portion of the second loop structuremember to the distal portion of the first loop structure member.
 18. Amethod as claimed in claim 10, wherein the step of connecting the distalportion of the second loop structure member to the distal portion of thefirst loop structure member comprises passing a pull wire through a pullwire guide.
 19. A method as claimed in claim 10, wherein the step oftightening the loop structure comprises moving the second loop structuremember proximally.
 20. A method of treating focal atrial fibrillation,comprising the step of: positioning a loop structure including anoperative element on the epicardial surface around a first pair ofpulmonary veins; creating a lesion with the operative element thatextends around the first pair of pulmonary veins; positioning the loopstructure around a second pair of pulmonary veins; creating a secondlesion with the operative element that extends around the second pair ofpulmonary veins; positioning a bendable linear structure including anoperative element on the epicardial surface between the first pair ofpulmonary veins and the second pair of pulmonary veins; and creating anelongate lesion with the operative element between the first pair ofpulmonary veins and the second pair of pulmonary veins.
 21. A method ofcreating a lesion on the outer surface of the bodily organ, comprisingthe steps of: positioning a closed loop structure including an operativeelement around the outer surface of the organ by positioning a firstloop structure member defining a distal portion adjacent to the organ,positioning a second loop structure member defining a distal portionadjacent to the organ with the distal portion of the second loopstructure member disconnected from the distal portion of the first loopstructure member without any physical structures extending beyond thedistal portion of the first loop structure member to the distal portionof the second loop structure member; and connecting the distal portionof the second loop structure member to the distal portion of the firstloop structure member to form the closed loop structure; tightening theclosed loop structure around the organ after the closed loop structurehas been formed; and actuating the operative element to create a lesion.22. A method as claimed in claim 20, wherein the step of positioning aclosed loop structure comprises positioning a closed loop structureincluding a plurality of spaced electrodes around the outer surface ofthe organ.
 23. A method as claimed in claim 21, wherein the step ofpositioning the second loop structure member comprises passing at leasta portion of the second loop structure member through the first loopstructure member.
 24. A method as claimed in claim 21, wherein the stepof connecting the distal portion of the second loop structure member tothe distal portion of the first loop structure member comprisesfastening the distal portion of the second loop structure member to thedistal portion of the first loop structure member.
 25. A method asclaimed in claim 21, wherein the step of connecting the distal portionof the second loop structure member to the distal portion of the firstloop structure member comprises passing a pull wire through a pull wireguide.
 26. A method as claimed in claim 21, wherein the step oftightening the loop structure comprises moving the second loop structuremember proximally.
 27. A method of creating an epicardial lesion,comprising the steps of: positioning a closed loop structure, includinga tubular member, a shaft that extends through the tubular member and isslidable relative to the tubular member, and an operative elementcarried by the shaft, around a portion of the epicardium; tightening theclosed loop structure around the portion of the epicardium by moving aportion of the closed loop structure proximally; and actuating theoperative element to create a lesion.
 28. A method as claimed in claim27, wherein the step of positioning a closed loop structure comprisespositioning a closed loop structure including a plurality of spacedelectrodes around the epicardium.
 29. A method as claimed in claim 27,wherein the step of positioning a closed loop structure comprisespositioning a closed loop structure around at least one pulmonary vein.30. A method as claimed in claim 27, wherein the step of positioning aclosed loop structure comprises positioning a closed loop structurearound a pair of pulmonary veins.
 31. A method as claimed in claim 27,wherein the step of actuating the operative element to create a lesioncomprises actuating the operative element to create a transmural lesion.32. A method as claimed in claim 27, wherein the closed loop structureincludes a pull wire and the step of tightening the closed loopstructure around the portion of the epicardium comprises pulling thepull wire proximally. and the